The Precision Approach Path Indicator (PAPI) system, as described in the FAA's “Precision Approach Path Indicator (PAPI) Systems” in FAA Advisory Circular AC 150/5345-28F, dated Apr. 12, 2005 provides a visual aid for pilots when landing an aircraft. The type of PAPI may be either a system consisting of 4 light units (L-880) or a system consisting of 2 light units (L-881). The light units are placed on one side of the runway in a line perpendicular to the runway centerline to define the visual glide path angle. The light units each have a white segment in an upper part of the beam and red segment in a lower part of the beam. The lights are positioned and aimed to produce a visual presentation wherein a pilot on or close to the established approach path (center) can determine his position relative of the glide path angle based on the colors of the lights as observed by the pilot.